The objective of this work is to continue to provide dosimetry support for epidemiologic studies of populations exposed to ionizing radiation. The studies include, but are not limited to, the following persons: women treated for cancer of the cervix, endometrium, and breast, as well as benign gynecological disease and infertility; children examined during management of scoliosis; children treated for all types of cancer and benign conditions, such as lymphoid hyperplasia and tinea capitis; men treated for peptic ulcer and cancer of the testes; and patients treated by neutron beams for all types of cancer. It is anticipated that other populations will be studied.